Over-the-range microwave appliances are generally mounted above a cooktop of an oven range appliance. In addition to providing for heating of food and beverage items, certain over-the-range microwave appliances include a circulation system. When activated, the circulation system can draw fumes, smoke, grease, and/or steam away from the cooktop of the oven range appliance. Circulation systems generally include a fan for drawing a flow of air into the circulation system and a grease filter for trapping grease entering the circulation system. Certain over-the-range microwave appliances also include air filters for filtering air passing through the microwave appliances' circulation systems. The circulation assembly's air filter can assist with removing dust, particulates, and/or other undesirable substances from air passing therethrough.
Over-the-range microwave appliances generally activate the circulation system's fan for a predetermined time interval in order to filter the air with the circulation system's air filter. After the predetermined time interval elapses, the fan is deactivated and the circulation system stops filtering air. A user can also manually deactivate the fan prior to the predetermined time interval elapsing in order to stop filtering air with the circulation system. Filtering air in such a manner has certain drawbacks. For example, the predetermined time interval can overly long such that the fan operates unnecessarily. Operating the fan excessively can be expensive, wasteful and noisy. As another example, the predetermined time interval can too short such that air is not adequately filtered.
Accordingly, a microwave appliance with features for assisting with filtering air with a circulation system of the microwave appliance would be useful. In particular, a microwave appliance with features for assisting with suitably filtering air with a circulation system of the microwave appliance without operating the circulation system's fan excessively would be useful.